Abstract
Expected changes in temperature, rainfall, water yield and surface runoff dynamics under RCP 8.5 were estimated in the Phetchaburi River Basin, Thailand, using outputs of five regional climate models. Observed temperatures and precipitations were downscaled using a combination of quantile mapping and nearest neighbour methods. The SWAT model was used to estimate changes in hydroclimatic variables in both the near-term (2006-2050) and long-term (2051-2099) temporal frames. All models predicted higher temperatures in the future (28.7-30.4°C) compared to the historical situation (28.0-28.3°C). The patterns of maximum temperature from most models were shifted one month earlier but there was no significant change for minimum temperature. Disagreement between models could be found in projected precipitations for the short term, but most of them pointed to an increase in rainfall in the long term, especially for maximum rainfalls ranging from 1,637 to 1,947 mm. CNRM-CM5 presented large differences in the future rainfalls compared to other models. Surface runoff/water yield significantly increased by 14%/17% in the long-term following the same trend as rainfalls with a slight change in the short-term.
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